1. Field of the Invention
The present invention relates to an inkjet print head forming an image by ejecting ink droplets and a method of manufacturing the inkjet print head. The invention particularly relates to an inkjet head having an insulating film within a pressure chamber from which an ink droplet is ejected.
2. Description of the Related Art
JP laid-open application publication No. 2002-160364 describes a so-called shear-mode inkjet print head that ejects an ink droplet from a nozzle using shear-mode deformation of a piezoelectric material. FIG. 8 is a sectional view of an inkjet print head of this type.
This publication describes a structure of an inkjet print head in an ink chamber of which a protection film is deposited to protect an electrode. This inkjet print head is comprised of a piezoelectric ceramic plate in which multiple grooves 117 and sidewalls 118 are formed with electrodes 119 being formed on sidewalls 118 of the internal surface of groove 117, an ink chamber plate covering the grooves to form ink chambers, and a nozzle plate in which multiple nozzles have previously been formed. There is deposited protection layer 120 on the internal groove 117 coating electrodes 119. The protection layer 120 consists of a inorganic insulating film 121 formed of an inorganic material and an organic insulating film 122 formed of an organic material, the former layer being formed first and deposited by the latter. Inorganic insulating layer 121, which is of silicon dioxide (SiO2), is formed in a thickness of 0.5 μm or more. As organic insulating layer 122, monochloroparaxylene is used, and the organic insulating layer is formed in a thickness of 5 μm or more.
In the process of fabricating the print head, after joining the ink chamber plate and ceramic piezoelectric plate in which electrodes 119 are formed, protection layer 120 is deposited. Then, the nozzle plate in which nozzles were previously formed is adhered to the ends of the joined plates.
To enhance positioning accuracy of nozzles with respect to the ink chambers, another process of fabricating the print head is practiced. That is, first, a ceramic piezoelectric plate in which a plurality of grooves, sidewalls, and electrodes on the internal surfaces of the sidewalls are formed, and an ink chamber plate covering the grooves thereby to form ink chambers are joined; a polyimide plate in which any nozzles are not formed yet is adhered to the formerly joined plates; then, nozzles are formed by the excimer laser processing being aligned with the respective ink chambers. In this fabricating process, the positional accuracy relative to each ink chamber can be enhanced compared to the process that a nozzle plate in which nozzles were previously formed is adhered to the joined plates.
The above-mentioned publication also describes an ink jet print head, to prevent deterioration of the electrodes by ink, which uses a ceramic piezoelectric plate in which electrodes are provided on the sidewalls on internal surfaces of grooves and the protection films formed of inorganic insulating film and an organic insulating film for protecting the electrodes are deposited over the electrodes. Herein, a nozzle plate with nozzles having being previously formed is adhered to the ends of the ink chambers. In this process, because of use of an adhesive to adhere the nozzle plate, an adhesive intrudes within the ink chamber, or some adhesive intrudes even into nozzles in some cases transforming the shape of the nozzle. This deformation of the nozzle shape varies the quantity of an ink droplet and its flight direction.
However, in this method of first providing joined plates of a ceramic piezoelectric plate in which electrodes and the protection films are deposited within the groves and the ink chamber plate covering the grooves to form the ink chambers, adhering a polyimide plate not having nozzles to the previously provided joined plates, and thereafter forming nozzles by the excimer laser processing aligning the nozzles to the respective ink chambers, a problem occurs that the protecting film damages.